Resilience in Quaking Aspen:
restoring ecosystem processes through applied science
Resilience in Quaking Aspen:
Restoring Ecosystem Processes Through Applied Science
High Lonesome Ranch, De Beque, Colorado
June 27-28, 2012
ORGANIZING COMMITTEE:
Paul Rogers
Samuel St. Clair
Cristina Eisenberg
Trent Seager
Scott Stewart
SPONSORS:
CONTENT
Back ground
1
Program
2
Speaker Abstracts
3
Participant Bio Briefs
9
BACKGROUND
Resilience in Quaking Aspen:
Restoring Ecosystem Processes Through Applied Science
Quaking Aspen (Populus tremuloides Michx.) is an oasis of local diversity, a regional
link in conservation corridors, and continentally our most widespread forest type. Its successful
establishment across diverse landscapes and environmental extremes demonstrates adaptability
as a species. However, recent reports of aspen decline suggest that current management
strategies and changing ecological conditions may impose constraints on aspen resilience in
some portions of its range. In contrast, other studies report areas in which aspen is persistent or
expanding. Clearly the ecological conditions that influence the sustainability and function of
aspen ecosystems are complex. How should we move forward given disparities in aspen’s
perceived status, physical settings, compositional associates, and functional processes? The
purposes of this symposium are to collectively, 1) gain an understanding of the “state of the
science,” including identifying research gaps, in quaking aspen studies; 2) think more deeply
about the critical questions ahead that that will better inform management and science; and 3)
document findings and recommendations with a goal of communicating outcomes to wider
audiences in several formats.
We chose the isolation and beauty of the High Lonesome Ranch to bring together key
researchers and managers to synthesize the current knowledge of aspen ecology and explore critical
knowledge gaps through presentations, synthesis, and goal-oriented discussion. Though we will
emphasize topics that have received a lot of attention of late—succession/disturbance dynamics
and aspen/ungulate interactions—we also wish to address less well known subjects covering a
range from basic to applied and physical to social realms. Our method will be “starter talks,"
follow-up discussion, and synthesis sessions. Additionally, A special issue of review papers from
the symposium will be published in Forest Ecology and Management in the coming year.
Published papers will follow a similar format as presentations, though we are hopeful that
relevant issues raised here will modify final submissions. Less formally, a field excursion, meals,
breaks, and free time will allow ample opportunity for individual and group interaction.
The genesis of this symposium stems from past efforts to bring members of the Western
Aspen Alliance (WAA) Science Advisory Panel (SAP) together in a single location. Our belief
was that if we could get an interdisciplinary team of "key players" into the field, we could
advance aspen sciences simply by facilitating novel idea exchange, as well as personal
connections. Secondarily, we hoped to make significant headway in prioritizing key research
issues facing land managers and aspen researchers....an ongoing SAP task. From the outset we
felt a relatively small group, ideally in a secluded setting, would provide the atmosphere to best
accomplish these goals. The current assembly still adheres to these objectives. Your active
participation here, with a bit of rumination time, will ultimately decide whether this approach is
fruitful.
1
PROGRAM
Wednesday, June 27
Thursday, June 28
7:30
BREAKFAST
12:00 LUNCH
8:30
8:45
9:05
Welcome & Introductions
Review Aspen Functional Types (Rogers)
Historical Cover Change (Kulakowski)
1:00
1:40
2:20
Facilitation and Competition (St. Clair)
Recent Mortality and Climate (Worrall)
Genetic Perspectives (Mock)
9:45
BREAK
3:00
BREAK
3:15
3:55
4:45
5:00
Social Science Insights (Clement)
Discussion: Clarify & Connect (Eisenberg)
Closing Thoughts
Adjourn
5:30
6:30
SOCIAL HOUR
DINNER
10:00 Aspen Fire Ecology (Shinneman)
10:40 Bark Beetle/Aspen Interactions (Pelz)
11:20 Discussion: Clarify & Connect (Rogers)
12:15 (sack lunch) Field Trip & Discussion
(Seager/Eisenberg)
Tour HLR aspen research projects
5:00 Return
5:30
6:30
SOCIAL HOUR
DINNER
Thursday, June 28
7:30
BREAKFAST
8:30
8:45
9:25
Field Trip Reflections
Aspen Defense Strategies (Lindroth)
Ungulate Herbivory (Seager)
Friday, June 29
7:30
8:30
BREAKFAST
WAA Science Advisory Panel
Business Meeting
11:00 Adjourn
10:05 BREAK
10:20 Trophic Cascades (Eisenberg)
11:00 Discussion: Clarify & Connect (St. Clair)
2
SPEAKER ABSTRACTS
(by order of presentation)
An Overview of Functional Classification for Western
North American Aspen (Populus tremuloides Michx.)
Paul C. Rogers, Simon M. Landhӓusser, Bradley D. Pinno, Ronald J. Ryel
Quaking or Trembling aspen (Populus tremuloides Michx.) forests occur in highly diverse
settings across North America. However, management of distinct communities has long relied on a single
aspen-to-conifer successional model. This presentation gives an overview of an more in-depth synthesis
paper currently in review. We examine a variety of stand types in the western portion of aspen’s range as
ecological systems; avoiding the narrow lens of exclusively seral dynamics or single species management.
Our framework describes three “functional types” with seven embedded “subtypes”: Seral (boreal,
montane), Stable (parkland, Colorado Plateau, elevation/aspect limited, terrain isolated), and Mixed SeralStable (riparian). Aspen functional types are defined as broad communities that differ markedly in their
physical and biological processes and interactions (i.e., functions). We build a case for unique functional
types based on our collective field experience and an extensive review of the literature. We distinguish
functional types based on physiological and climatic conditions; stand compositions, structures and
dynamics; and disturbance types and periodicity. Additionally, we examine some overarching challenges,
such as human alterations, ungulate herbivory, and climate futures, that are or will impact the
functionality of these aspen systems. Finally, we explore short- and long-term management
considerations for each aspen type. The functional framework lends itself well to management and
research that seeks to understand and emulate ecological processes rather than combat them. There may
be advantages of applying this classification approach to other vegetation communities whose broad
distributions engender diverse adaptations.
Long-term aspen cover change in the western U.S.
Dominik Kulakowski, Margot W. Kaye, and Daniel M. Kashian
Abstract: Quaking aspen (Populus tremuloides Michx.) is one of the most important tree species
in the western United States due to its contributions to biodiversity, tourism, and other aesthetic and
ecological values. Much recent attention has focused on long-term changes in aspen forests, which may
include potential broad-scale decline or potential broad-scale expansion depending on the region in
question. Compared to other forest types in the western United States, the inquiry into long-term aspen
dynamics has been encumbered by methodological limitations, including the fact that aspen are relatively
short-lived and prone to heart-rot, which has made long-term dendroecological studies difficult. Where
reported, often extensive aspen decline has been linked to warm and dry climatic conditions and also to
ungulate herbivory, insect herbivory, and/or fire suppression. Climatically driven aspen mortality may
have also occurred in past centuries and may have been followed by stand-level aspen regeneration.
While recent climatic trends appear to have direct detrimental effects on aspen vigor, widespread forest
fires and bark beetle outbreaks in adjacent coniferous forests may have set the stage for an expansion of
aspen dominance as recent research has reported asexual and sexual reproduction of aspen in stands once
dominated by conifers. Such a potential conversion of conifer to aspen forests may lead to possible
feedbacks to future disturbance regimes and landscape dynamics. Important goals for future research
include understanding how broad-scale, long-term aspen dynamics vary across geographic and
biophysical gradients; how climatic variability is linked to aspen mortality; and the determinants of
successful sexual reproduction of aspen, which may be more common and important to aspen landscape
dynamics than previously thought. Fertile areas for research may include opportunistic studies of aspen
response to recent fire or beetle outbreaks, experimental fire and mock beetle outbreak studies to identify
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mechanisms underlying aspen response to disturbance, differential aspen response to climate variability
on sites of varying quality, spatially-explicit modeling of aspen population dynamics, and high-resolution
remote sensing of aspen distribution and condition.
Fire regimes of quaking aspen in the Intermountain West
Douglas J. Shinneman, William L. Baker, Dominik Kulakowski, and Paul C. Rogers
Quaking aspen (Populus tremuloides Michx.) is the most widespread tree species in North
America, and it is found throughout much of the Intermountain West across a broad range of bioclimatic
regions. Aspen typically regenerates asexually and prolifically after fire, and due to its seral status in
many western conifer forests, aspen is often considered dependent upon stand-replacing disturbance for
persistence. In many landscapes, historical evidence for post-fire aspen establishment is clear, and
senescing or declining aspen overstories often lack abundant regeneration and are succeeding to conifers.
However, aspen also forms relatively stable stands that contain little or no evidence of historical fire. In
fact, research suggests that aspen woodlands range from being highly fire-dependent, seral communities
to relatively stable, self-replacing, non-seral communities that do not require fire for persistence. Given its
broad geographic distribution, aspen fire regimes likely co-vary spatially with changing community
compositions, stand structures, landscape settings, and climate conditions, and temporally with past land
use effects and climate. Moreover, multiple change agents are likely contributing to aspen population
dynamics in the western U.S., including climatic fluctuation (e.g., drought), insects, disease, and
browsing of young aspen by livestock and wildlife. The interacting historic roles of fire and other
disturbance agents in aspen population dynamics are often poorly understood, especially at regional
scales. Here we review the literature to summarize aspen fire regimes in the western U.S. and highlight
gaps in our knowledge. We also suggest a classification framework for aspen fire regimes that is tightly
coupled with biophysical settings that support different functional aspen types. Such a classification will
likely require additional research using spatial analysis, dendrochronology, experimental manipulation, or
other techniques. However, providing an appropriate disturbance ecology context should aid efforts to
manage and restore aspen communities, and help to diagnose key factors contributing to documented
changes in aspen cover.
Aspen response to mountain pine beetle disturbance in the central Rockies, USA
Kristen A. Pelz and Frederick W. Smith
There has been speculation that aspen (Populus tremuloides) abundance will increase due to
mortality of lodgepole pine (Pinus contorta var. latifolia) caused by mountain pine beetle (Dendroctonus
ponderosae; MPB) in the central Rocky Mountains. Pulses of regeneration via aspen sprouting have been
observed following overstory conifer mortality due to mountain pine beetle and spruce bark beetle in
Utah, Colorado, and Wyoming. However, it is unclear if this forest disturbance will result in increased
aspen overstory, as growth of aspen sprouts into the overstory will be limited by many factors. Surviving
conifer overstory and advance regeneration may limit light and other resources, reducing aspen sprout
growth and survival. Soil conditions could prevent significant aspen growth following MPB because
macronutrients and mycorrhizal associates of aspen may be less prevalent at conifer-dominated than
aspen-dominated sites. Ungulate browsing has been shown to prevent aspen growth into the overstory if
browsing pressure is high. Finally, climate and weather variability will mediate aspen response to MPB.
Drought during the early 2000s has been tied to sudden aspen decline throughout the central Rockies. If
years with low precipitation and snowpack follow MPB-caused mortality, aspen on drier sites may die
rather than growing into a larger component of the overstory. Overall, aspen may increase in abundance
following MPB in areas where it is not outcompeted by shade-tolerant tree species and ungulate browsing
pressure is not excessive if weather conditions allow for aspen growth and survival.
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Herbivore Defense Strategies in Aspen
Richard L. Lindroth and Samuel St. Clair
Aspen (Populus tremuloides) is a quintessential “foundation species” in early-successional forest
ecosystems throughout northern and western North America. Although subject to damage by hundreds of
species of herbivores, aspen has persisted in these environments due largely to a suite of defense
strategies, including resistance, tolerance, and escape. Resistance traits (e.g., secondary compounds)
reduce herbivore damage, tolerance traits (e.g., accelerated photosynthesis) facilitate recovery from
herbivore damage, and escape traits (e.g., rapid vertical growth) reduce the incidence of damage.
The principal secondary compounds in aspen are phenylpropanoid-derived compounds, including
phenolic glycosides (salicylates) and condensed tannins. Phenolic glycosides have been shown to reduce
feeding and fitness of insect herbivores, and to deter feeding by ungulates. Levels of foliar phenolic
glycosides are strongly influenced by tree age: concentrations are exceptionally high in young
trees/ramets, and decline with age, suggesting that mammalian herbivores played an important role in
determining patterns of expression.
All of the major categories of defenseresistance, tolerance and escapeexhibit striking
variation among aspen genotypes/clones. They also exhibit negative genetic correlations with each other.
For example, across genotypes, levels of foliar phenolic glycosides are negatively correlated with tree
growth rate. Thus, investment in one form of defense comes at a cost of other forms of defense. Finally,
environmental factors such as soil nutrient availability and light environment modulate defense compound
production in aspen.
The efficacy of aspen defense systems is context dependent. Under conditions of low to moderate
herbivore pressure, chemical defenses serve as effective deterrents. Under conditions of high herbivore
pressurewhether insect or mammalresistance fails and trees sustain high levels of damage. Under
these conditions, genotypes with high levels of tolerance will be favored by selection.
High levels of damage by insects, wildlife or livestock decrease the resilience of aspen
ecosystems. A clear understanding of aspen susceptibility and defense against herbivory is vital in
managing for properly functioning aspen forest.
The Ecology and Impacts of Aspen-Ungulate Interactions: a Review
S Trent Seager and Cristina Eisenberg
Quaking aspen (Populus tremuloides) ecosystems in the Western US contain high levels of
biodiversity with an especially rich plant life. Wild ruminant herbivores (primarily elk, Cervus elphus,
and deer, Odocoileus spp.) depend on these ecosystems for critical food and habitat. Yet intense
browsing may degrade aspen ecosystems, simplifying food web processes and structure, and having
negative implications for ecosystem resilience. While ungulates have utilized aspen stands for thousands
of years, recent human-caused changes in climate, land-use, and wildlife management have altered
historic patterns. Here we review the ecology and current impacts of aspen-ungulate interactions in the
Western US. Ungulates utilize high-quality forage in aspen ecosystems, including aspen sprouts, which
retain high-protein content year-round. While ungulates browse aspen sprouts throughout the year, use of
aspen by elk is both seasonally and ecologically different from that of deer. Mild to moderate browsing
may increase understory heterogeneity. Long-term and high-levels of browsing have a negative effect on
aspen sprout and stem recruitment, including preventing cohorts from reaching the canopy (missing age
classes). Further, mature aspen stems may be damaged by elk feeding on the bark during winter, leading
to secondary agents and potential death of the mature stems. Research has linked herbivory to both longterm and recent aspen decline in some areas. Key knowledge gaps include a more integrated
understanding of how a variety of stressors (e.g., disease, insects, climate, fire) may work together with
chronic herbivory to impact aspen resilience. Given the prioritization to restore aspen ecosystems in this
5
time of rapid global change, and the ecological value of this species, achieving a more integrated
understanding of large herbivore impacts on aspen is essential.
Trophic Cascades in Aspen Communities: Insights and New Horizons
Cristina Eisenberg, S Trent Seager, and David E. Hibbs
Trophic cascades are ecological relationships in which an apex predator produces direct effects
on its prey and indirect changes in faunal and floral communities at lower trophic levels. Like most
ecological communities, aspen (Populus tremuloides) forests are structured by a synergy of bottom-up
(resources-driven) and top-down (predator-driven) effects. In recent years, the decline of aspen
communities throughout the Intermountain West has received considerable research attention. The extent
and possible drivers of this decline are topics of much scientific debate. In addition to bottom-up effects,
which include drought, fire suppression, and disease, ungulate herbivory has been recognized as a
contributing factor. Further, apex predators, such as the gray wolf (Canis lupus), have been linked to
aspen conservation status, via trophic cascades mechanisms. Aspen provides a key food source for elk
(Cervus elaphus) and deer (Odoileus spp.). Scientists have hypothesized that returning wolves to the
landscape enables aspen to recruit into the forest overstory, via the density-mediated and behaviorallymediated effects of wolves on their ungulate prey. Here we present a synthesis of scientific findings on
this topic, identify trends in the ecological impacts of apex predators in aspen communities in a variety of
ecosystems, and suggest areas for further investigation. Knowledge gaps include the interaction of topdown (e.g., predators) and bottom-up (e.g., drought, fire) effects. Future horizons involve exploring food
web relationships as a complex of inter-level interactions in a more integrated, quantitative manner. Such
an integrated approach to trophic cascades science can help managers create more resilient aspen
communities.
Facilitation and competition in aspen forests
Samuel St. Clair
Across its expansive range, quaking aspen commonly associates with conifers to form mixed
forests. The composition and structure of mixed aspen-conifer forest are influenced by patterns of
secondary succession driven by competition and timing of disturbance events. There is increasing
evidence that facilitation between aspen and conifers alters competitive interactions in ways that strongly
influence aspen-conifer forest development. Observations show that conifers establish abundantly under
young aspen stands during the early stages of secondary succession and that conifer seedlings tend to
aggregate at base of aspen trees, creating the potential for competitive interactions in later life stages.
Recent studies indicate that facilitation of conifer seedlings by aspen increases aspen and conifer
proximity that promotes competitive interactions in later stages of stand development. This association
resulted in high aspen mortality rates that likely contribute to compositional shifts in aspen-conifer
forests. These findings provide important insights for the sustainable management of seral aspen forests.
The maintenance of natural disturbance regimes appears to be important in striking an ecological balance
between facilitative and competitive interactions that promotes the proper development of these forest
systems. Because of aspen’s primary role in initiating secondary succession through post-disturbance
sucker regeneration, and the subsequent dependence of conifers on aspen for establishment, aspen
mortality via competition with conifers under longer fire cycles, drought or intensive ungulate browsing
may result in a loss of aspen-conifer forest communities. This is especially true in the Interior West of the
US because aspen regeneration is largely an asexual process that depends on suckering from living root
systems. We have observed several instances where intensive elk grazing of regenerating aspen suckers
following disturbance have resulted in complete aspen mortality. Fifteen years later these areas that were
once thriving mixed aspen-fir forests are now grasslands with no evidence of aspen or conifer
regeneration. This paper will synthesize insights and identify knowledge gaps related to facilitative and
6
competitive interactions in aspen-conifer forests, and how they are altered by climate change, herbivory
and changing disturbance regimes.
Recent mortality episodes of Populus tremuloides and climate in North America
James J. Worrall, Edward H. Hogg, Gerald E. Rehfeldt, Michael Michaelian ,
Andreas Hamman , Suzanne B. Marchetti, and Laura Gray
We review historical and especially recent episodes of extensive crown thinning, branch dieback,
and mortality in Populus tremuloides (quaking or trembling aspen) in North America, and examine
indices of moisture stress, insect defoliation and other factors as potential causes. Attention is focused on
regions where extensive aspen mortality has been documented in recent years. These include the southern
Rocky Mountains and Colorado plateau, the aspen parkland transition between prairie and boreal forest in
western Canada, and the boreal shield of eastern Canada and the northern Lake States. Analysis of the
historic climate records shows that these regions have experienced significant warming, coupled in most
cases with exceptionally severe droughts over the past decade. Collectively, recent research indicates that
these exceptional droughts were a major cause of aspen dieback, mortality and growth reductions,
especially in the drier regions of western North America. Other factors, notably multi-year defoliation by
tent caterpillars (Malacosoma spp.) and stem damage by fungi and insects also play a substantial role in
mortality episodes, and may amplify or prolong the impacts of drought on aspen over large areas. As a
clonal species, aspen normally has the capacity to regenerate rapidly through root suckering following
stand-replacing disturbances such as fire. However, assessments of drought-affected stands with high
mortality indicate that regeneration potential in some cases is poor, which raises concerns that climatic
drying could ultimately lead to a widespread loss of aspen forest cover. Although aspen is very widely
distributed and successful in a broad array of habitats, in many parts of its range it appears to be quite
sensitive to climatic fluctuations, particularly droughts. Using a newly developed range-wide climate
profile, coupled with general circulation models used by IPCC, we examine the projected changes in
distribution of climate suitable for aspen toward the end of this century. Projections suggest that as the
climates suited to the boreal forests shift northward and those of the subalpine forests are pushed
upwards, suitable habitat for aspen will diminish.
Western aspen (Populus tremuloides): molecular tools,
changing perspectives, and future directions.
Karen E. Mock, Bryce A. Richardson, and Paul G. Wolf
Aspen (Populus tremuloides) is an iconic species in western North American landscapes, highly
valued for recreation, wildlife and livestock forage, biodiversity, and as a fuelbreak. However, there are
rising concerns about the ability of aspen to persist in these landscapes, based on bioclimatic modeling
and mortality surveys. Our ability to mitigate aspen decline will depend on our understanding of the
factors influencing aspen establishment and persistence. Genetic techniques are providing important
insights about reproductive strategies, evolutionary and demographic histories, and adaptive capacity in
western aspen, often with important and novel management implications. A suite of new genetic tools is
also becoming available as a result of innovations in genetic sequencing technology, along with the
availability of an annotated reference genome for Populus species. Here we provide 1) an overview of
the traditional and emerging molecular tools that can be useful in understanding aspen ecology, including
both opportunities and limitations, 2) a summary of the ways in which these tools are already changing
our perceptions of aspen spatiotemporal dynamics, and 3) a synthesis of future questions that can be
addressed using these tools. Our goal is to provide an informational resource to forest managers about the
utility of traditional and emerging genetic tools, with specific relevance to aspen ecology and
management.
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Human Dimensions of Aspen
Jessica M. Clement
This Symposium will allow participants to unravel much of the complexity of the biophysical
factors related to aspen forests in the West. A review of the literature related to the human dimensions of
aspen forests provides little quantitative insight into the non-monetary connections between humans and
aspen forests and yet attachment in historical documentation regarding the value of aspen trees and forests
is described. The relevance of these dimensions are likely to increase as trade-offs regarding budgets,
land uses, wildlife species preservation, recreational behaviors need to be included in any land
management decision making regarding aspen trees and forests. Additionally, these less tangible, often
emotional, connections to natural resource elements are often the strongest motivating factors among
citizens (i.e., non-scientists).
This presentation will focus on two topics:
a. A brief review of the social science and historical literature regarding the various non-monetary
connections that humans have with aspen forests with a discussion of possible implications for
land management.
b. An exploration with symposium attendees of social science questions that need to be addressed
by the scientific community that would aid land management decision making.
The deliverable of this to the symposium will be a review of social science related to aspen on the
one hand, and a deliberated research agenda on the other. In this way, we hope to provide a firm starting
point for social scientists interested in delving into aspen-related topics more seriously.
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PARTICIPANT BIO BRIEFS
Gregory H. Aplet—Senior Forest Scientist in The
Wilderness Society’s Denver office. He holds degrees in
forestry from U. C. Berkeley and a Ph.D. in forest
ecology from Colorado State and has written about Rocky
Mountain and Hawaiian forest dynamics, biological
invasions, biodiversity conservation, and wildland fire
and wilderness management. [email protected]
Dale L. BartosResearch Ecologist with the Forests and
Woodland Ecosystem Program, Rocky Mountain
Research Station, Logan, Utah. He holds a Ph.D. (1972)
degree in Range Science from CSU, Ft. Collins,
Colorado.
His principal research interests are in
ecological processes in general and restoration of aspen
landscapes. [email protected]
Jessica M. ClementHas conducted human dimensions
in natural resources research related to forest issues in
western U.S. for 20 years. She has degrees in journalism
and natural resource management, concentrating on forest
issues and social psychology.
She works as an
independent consultant in human dimensions research,
collaborative governance, and natural resource policy.
[email protected]
Cristina EisenbergPhD from Oregon State University
and is a Boone & Crockett Fellow. She is the research
director on the HLR, and studies trophic cascades and
food web complexity in aspen. Her book The Wolf’s
Tooth: Trophic Cascades and Biodiversity was published
by
Island
Press
in
2010.
[email protected]
Mark Fowden—Assistant Chief of Fisheries, Wyoming
Game and Fish Department. The role of aspen for
maintaining watershed functions that benefit aquatic
wildlife (fish, amphibians, and invertebrates) is still not
fully appreciated. Use of beaver to restore and degraded
watersheds associated with aspen communities is a
priority
for
department
biologists
.
[email protected]
Beth Haley—Education and Research Coordinator at the
High Lonesome Ranch. Her background is in
conservation biology and she is currently pursuing a
Master of Arts degree at Prescott College in
Environmental Studies with an environmental education
concentration. [email protected]
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Katie Ireland—PhD student in the School of Forestry at
Northern Arizona University. Her research is focused on
understanding historical links between climatic
conditions, forest fires, and forest communities, including
the relationship between climate and aspen mortality and
growth in northern Arizona. [email protected]
Jason Kirkey—working toward his MA in conservation
biology. His research focuses on trophic relationships in
aspen forest communities. He holds a prior MA in
philosophy. [email protected]
Dominik
Kulakowski—Assistant
Professor
of
Geography at Clark University. His scientific interests
include forest dynamics, natural disturbances and
landscape ecology. His work on quaking aspen has
focused on long-term variations in aspen cover, climatic
influences on aspen mortality, and the effects of
compounded disturbances on aspen regeneration.
[email protected]
Rick LindrothProfessor of ecology and Associate
Dean for Research at the University of WisconsinMadison. His research group investigates how genetic and
environmental factors, including climate change, shape
the chemical composition of aspen, and the consequences
of plant chemistry for ecological interactions and
evolutionary relationships. [email protected]
Karen Mock—Associate professor at Utah State
University. Her research group is working on several
aspects of aspen genetic diversity and ecology. Her lab is
also involved in the molecular ecology of several other
species, including mountain pine beetles, freshwater
mussels, Phragmites australis, and leopard frogs.
[email protected]
Kristen Pelz—PhD student in the Graduate Degree
Program in Ecology and Department of Forest and
Rangeland Stewardship at Colorado State University. Her
research is focused on stand- to landscape-scale effects of
disturbances and forest management on subalpine forest
of the southern Rockies. [email protected]
Claudia Regan—Regional Vegetation Ecologist,
US Forest Service, Rocky Mountain Region
and Affiliate Faculty Department of Forest, Rangeland,
and Watershed Stewardship, Colorado State University.
[email protected]
Roy Renkin—Currently a Supervisory Vegetation
Specialist in Yellowstone, he began his NPS career in
Yellowstone in 1979 in the Division of Forestry and Fire
Management. Roy’s long interest and publications in the
Yellowstone
aspen
story
includes
fire/root
biomass/suckering relationships, postfire seedling
establishment, browsing issues, and monitoring for
regeneration. [email protected]
Samuel St. ClairAssistant Professor of plant
physiological ecology at Brigham Young University. His
research explores how plant responses to abiotic (climate,
fire) and biotic factors (facilitation, competition,
herbivory and pollination) influence the function of forest
and desert ecosystems. [email protected]
Douglas Shinneman—Research Fire Ecologist with the
USGS Forest and Rangeland Ecosystem Science Center
(Boise). His research investigates how plant communities
and disturbance regimes are influenced by land use,
nonnative species, and climate, with projects in aspen
woodlands, Rocky Mountain forests, boreal forests,
pinyon-juniper woodlands, and sagebrush shrublands.
[email protected]
Julia RichardsonSince July 2011,
Regional
Silviculturist for the Intermountain Region, Ogden UT;
previous experience involved silviculture and vegetation
management on the following National Forests (NF):
Humboldt-Toiyabe NF in Nevada, Colville NF in N.E.
Washington, and on the Willamette and Umpqua NF’s in
Western Oregon; Certified Silviculturist since 1988.
[email protected]
Paul R. Vahldiek—Chairman and CEO of The High
Lonesome Ranch. Paul has a J.D. from St. Mary's
University School of Law. He is a board member of Trout
Unlimited's Coldwater Conservation Fund, Bonefish &
Tarpon Trust, Wildlands Network, Theodore Roosevelt
Conservation Partnership, and a regular member of the
Boone & Crockett Club. [email protected]
Paul C. RogersDegrees in geography from Utah State
University (BS) and University of Wisconsin-Madison
(MS) and ecology (USU; PhD). Paul works in
biogeography, aspen ecology, lichenology, and landscape
monitoring. He is currently adjunct faculty in USU's
Wildland Resources Department, Ecology Center
Associate, and Western Aspen Alliance Director.
[email protected]
Thomas T. Veblen—Professor of Geography at CU
Boulder conducts research on the history and interactions
of ecological disturbance (fire, wind, insect outbreaks)
and their consequences for forest dynamics in the context
of climatic variability. His current projects include work
in Colorado, southern Chile and Argentina, New Zealand
and Tasmania. [email protected]
Ronald J. Ryel—Associate Professor in plant
ecophysiology at Utah State University. His research foci
include investigating how plants through physiological
processes affect ecosystem function, and developing and
teaching natural resource science. Specific to aspen, he is
working on aspen functional type classification, aspen
ecohydrology,
and
assessing
aspen
[email protected]
Aaron Wilkerson—Forestry Program Lead, Bureau of
Land
Management,
Salt
Lake
City,
Utah.
[email protected]
James J. Worrall—Attended graduate school at
University of California, Berkeley, then did research at
Göttingen University in Germany and University of New
Hampshire. He was Assistant and Associate Professor in
the College of Environmental Science and Forestry at
SUNY before joining the USFS Rocky Mountain Region
as a Forest Pathologist. [email protected]
Trent SeagerPhD student in Forest Ecology at Oregon
State University. His MS research focused on herbivory
effects on aspen persistence across multiple landscapes.
Trent is an aspen ecologist for the HLR, where he studies
aspen recruitment dynamics as part of their trophic
cascades research. [email protected]
10
Aspen Rain
Sunlight captured on trembling trees
the rarest of gold in her shimmering leaves
a chill wind comes along
and the branches shiver
summer whispers goodbye while the aspens quiver
with regal grace the proud limbs
unbutton their gowns.
The leaves enjoy one last dance
as they flutter down
lone branches creak softly as they swear an oath;
new life shall return with their spring growth,
and death flaunts her beauty
where no gold remains:
trees dance naked in the aspen rain.
--Jeanne MacGregor Lahn